Proposed Changes to the Canadian Drinking Water Guidelines and Possible Impacts Based on a Case Study of Lead in Drinking Water in the Lower Mainland

By Chris Taylor

In January, Health Canada announced a proposed change to numerous compound standards in the Canadian Drinking Water Guidelines. While there are several items of note, of particular impact may be the proposed changes to the lead standard.

The current standard is an allowable level of 0.01 mg/L taken from a “flushed” sample where the water runs for a set period of time; the proposed standard drops this to 0.005 mg/L for locations such as schools and requires that the sample (in most instances) now be taken from the “static” sample or from the initial draw of the water.

As a firm, our policy has been to routinely collect static samples along with flushed samples as a means of helping diagnose whether or not potential lead contamination was coming from the municipal water supply, or from within the interior water systems of the building. In this particular area, the municipal water systems reported testing regularly for lead – but only using the flushed collection method (with all reported results being below the current guideline). In reviewing our data, while we did find several schools where lead-containing piping/fixtures were having an impact on delivered water quality, nearly all static samples collected nearest the municipal source were returning results above the existing guideline. Suspecting an issue related to the municipal systems, we were able to collect samples from outdoor hydrants extremely close to the connection points to the municipal systems and again, a very high percentage exceeded the current guideline in the static sample.

Based on this data set, and our experience in other jurisdictions, we know that if all Health Canada did was change the standard by changing from flushed to static samples, let alone cutting the standard in half, essentially all the drinking water in that region would fail the guideline. Based on other, more limited, data that we have collected, this would likely be the case in most municipalities. While it is difficult to debate a standard that is being proposed to better protect children, the logistical impacts of this change, we feel, will be significant and costly. Forewarned is forearmed.